Available in 19 countries from 1 January 2013: Mercedes-Benz eCall emergency call system - faster help at the crash scene

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In June 2012, three years ahead of the planned obligatory date set by the European Commission, Mercedes-Benz eCall, the vehicle emergency call system, was launched. In the event of a serious accident, the emergency services can be notified automatically and be informed of the precise location of the accident and the car model within just a few minutes. The Mercedes-Benz emergency call system is standard in the latest version of the COMAND Online multimedia system. Except for possible mobile phone charges, the Mercedes-Benz emergency call service is completely free of charge to Mercedes-Benz customers. The service is now available in nineteen European countries.

After a serious accident every second counts. The Mercedes-Benz emergency call system uses this crucial phase and can notify the emergency services automatically after a serious crash. If the airbags or belt tensioners are deployed and COMAND Online is linked to a mobile phone, the precise GPS position of the vehicle and the vehicle identification number (VIN) are sent via text message (SMS) to the emergency call centre of the Bosch Communication Center, and at the same time the location data are transmitted via DTMF (dual-tone multi-frequency signalling). Even if the occupants are unconscious, or for example are on holiday and do not know exactly where they are, the Communication Center can inform the emergency services quickly and precisely.

In addition, the vehicle will quickly set up a call to the Bosch Communication Center. And a particularly practical feature which can be helpful in an emergency: the call is not conducted in the language of the country, but in the language which the driver has programmed in to COMAND Online. An emergency call can also be made manually, as "Mercedes-Benz emergency call" is always the first entry in the phone book. Geographically, eCall is being phased in in several stages: on 1 June 2012 the automatic emergency call system was introduced in nine European countries – Germany, France, Italy, Spain, the UK, Austria, Belgium, the Netherlands and Switzerland. From 1 January 2013, ten more will follow: Norway, Finland, Lithuania, Hungary, Romania, Bulgaria, Greece, Portugal, Luxemburg and Malta.

As part of the eSafety initiative, the European Commission has ruled that by 2015 eCall technology should be available in all new cars. EU Commission sources have found that with the help of an immediate eCall giving the coordinates of the accident scene, the time the emergency services take to arrive could be reduced by 50 percent in rural areas and 40 percent in towns. This could mean up to 2500 fewer road deaths per year in the EU.

Credits: Daimler AG

Copyright © 2012, mercedesgla. All rights reserved.

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Mercedes-Benz 4MATIC: All-wheel drive for all – in every class

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Each year during winter time, Mercedes-Benz heads over to the icy cold Hochgurgl resort in the Austrian Alps along with its fleet of off-road competent and capable vehicles equipped with the revolutionary 4MATIC traction system. In 2012, the Germans deployed their new CLS Shooting Brake, GL and GLK models to take a journey on the snow-covered alpine roads. Moreover, this event also served as a preview for the new addition in the compact class lineup: the CLA, which celebrates its world premiere in January 2013 at NAIAS Detroit.

With this occasion, Mercedes-Benz took the challenge to emphasize the versatility of the state-of-the-art 4MATIC all-wheel-drive system, which can be easily adapted across the entire range of models that wear the Star, from the A-Class and CLA-Class up to the classic G-Class, going through the C-, E-, S-, CL-, CLS-, GL-, GLK-, M- and R-Class. The introduction of the new version that was specially developed for compact-sized, front-driven vehicles heralds the advent of the new A 45 AMG performance hatchback, as well as the advent of the new CLA 45 AMG super 4-door coupe, both slated to arrive next year.

Check out more details and pictures through following the next links:

- The summit of perfection with new 4MATIC: All-wheel drive for all – tailor-made solutions

- 4MATIC for the compact model range from Mercedes-Benz: Greater driving dynamics, greater traction, greater safety

- On track of CLS and Co.: 2013 premiere for CLA and CLA 45 AMG

- Elegant in all weathers: the CLS 4MATIC Shooting Brake in the snow

- The new GL- and GLK-Class: Effortless superiority on- and off-road

Enjoy! :)

Copyright © 2012, mercedesgla. All rights reserved.

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4MATIC for the compact model range from Mercedes-Benz: Greater driving dynamics, greater traction, greater safety

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The most innovative components of the new 4MATIC include the power take-off to the rear axle which is integrated in the 7G-DCT automated dual clutch transmission and the rear-axle gear with integrated, electrohydraulically controlled multi-disc clutch. This set-up enables fully variable distribution of the drive torque between front and rear axle. Additional benefits of this design are a lower system weight than is available from the competition and high efficiency.

The 4MATIC all-wheel drive is a completely new development tailored to the requirements of the new front-wheel drive architecture. The engineers at Mercedes-Benz have ventured into uncharted territory here, as the design of the previous model series ruled out the introduction of an all-wheel drive system based on a front-wheel drive architecture with transversely mounted front engines. On these previous models the differential was located in front of the engine in the direction of travel, thus thwarting any options of diverting drive power to the rear axle. In addition, the body design with sandwich floor prevented the integration of a cardan shaft to the rear axle.

For the new front-wheel drive vehicles, adequate installation space for an all-wheel drive powertrain was provided right from the initial stages of the planning process. In addition, the development engineers designed the powertrain such that the differential axle is situated behind the engine, thus enabling power to be branched off to the rear axle. The future all-wheel drive line-up from Mercedes-Benz will be heralded in the coming year by the new CLA and the particularly agile and powerful CLA 45 AMG. While the basic mechanical configuration is identical on all versions, the AMG models feature a modified power output to the rear axle.

Integrated power take-off unit (PTU) channels power to the rear axle

The new 4MATIC is being combined with the 7G-DCT seven-speed automated dual clutch transmission which was premiered in the B-Class. The power flux to the rear powertrain is provided by a compact power take-off unit (PTU) which is fully integrated in the main transmission and is supplied with lubricant from the latter's oil circuit. This configuration gives rise to substantial weight advantages in comparison to rival systems which branch off power by means of an add-on component with its own oil circuit. Together with the friction-minimised tapered roller bearings, the PTU achieves an excellent level of efficiency.

The low system weight of the new 4MATIC is not attributable solely to the PTU. Other weight-stripping measures include a compact rear-axle gear unit, inductively hardened rear-axle side shafts in hollow design and weight-optimised propeller shafts. The system weight of the new 4MATIC is up to 25 percent lighter than the all-wheel-drive versions offered by the competition. These lightweight design measures and the high functional efficiency result in a good level of energy efficiency.

As is always the case with all-wheel drive systems incorporating a transversely mounted drive unit at the front, the power flux requires to be diverted by 90 degrees. On the 4MATIC, this is achieved by quite simple means: the differential gearwheel of the main transmission drives the spur gear of the PTU and a compact bevel gear stage diverts the power flux. The rear axle is driven via an output flange and a cardan shaft.

A vibrationally decoupled intermediate bearing is fitted between the two-part cardan shaft and underbody and a flexible coupling is installed between the shaft and the rear-axle gear unit. An axially moving joint at the front compensates the typical movements of the engine-transmission unit under load and prevents the transfer of such movements to the rear powertrain. By virtue of these measures, all the 4MATIC versions attain a level of NVH comfort on a par with that of the comparable models with front-wheel drive. In order to minimise crash-induced stress for passengers in a head-on or rear-end collision, the cardan shaft is provided with a crash joint. Here again, the 4MATIC models attain a standard of safety on a par with that of the front-wheel drive models.

Completely new development with torque-on-demand rear axle

The electrohydraulically actuated multi-disc clutch integrated in the rear-axle gear unit is responsible for fully variable torque distribution. Operating principle: when the multi-disc clutch is open, the CLA is driven almost exclusively by the front axle. When the clutch is closed, the rear axle comes into play. This means that the drive torque can be shifted in fully variable mode between front and rear axle according to the given situation (torque on demand).
The system pressure to activate the rear axle is supplied in milliseconds by the rotor pump which is integrated in the rear-axle gear unit. The pump is activated automatically as soon as only minimal speed differences apply between front and rear axle. Pressure control is performed by a proportioning valve under the steering of the ESP®.

The most diverse parameters are taken into consideration here, such as lateral acceleration, steering angle, yaw rate, accelerator position, ABS control settings or the selected shift programme of the 7G-DCT dual clutch transmission. An additional pressure regulating valve limits the drive torque at the rear axle to 750 Newton metres. Up to 1000 Newton metres are possible on the AMG version.

Intelligent control systems for more enjoyable driving

The 4MATIC is activated according to the basic principle of "as often as necessary as rarely as possible". This means that when the underlying conditions allow the all-wheel drive CLA models run almost exclusively in front-wheel drive mode. As soon as the driving situation requires, additional drive torque is channelled to the rear axle as appropriate. The reverse process takes place just as quickly: as soon as additional drive torque is no longer expedient at the rear axle – e.g. in case of heavy braking manoeuvres with ABS intervention – the rear powertrain is deactivated and torque is reduced to zero. With this strategy, the developers have managed to combine two key requirements defined in the performance specifications: optimum energy efficiency coupled with maximum driving dynamics and driving safety.

In normal circumstances, the drive torque distribution between front and rear axle can be set from 100:0 to 50:50. In certain driving situations, such as when exceeding the µ-jump limit, higher levels of torque may be allocated to the rear axle to avoid unstable operating conditions. Here are some examples of torque distribution (front:rear in percent, approximate values):

- Full-load acceleration at approx. 50 km/h → 60:40

- Dynamic cornering under load → 50:50

- Exceeding the µ-jump limit → 10:90

- Heavy braking with ABS intervention → 100:00

Another basic principle of the 4MATIC system results in a further increase in driving dynamics, guaranteeing greater driving enjoyment without compromising driving safety. In case of understeering or oversteering under load, the drive torque is first of all distributed such as to stabilise the vehicle. This ensures that traction and driving enjoyment are fully maintained in speedy driving on winding stretches of road. Only if these measures fail to have a stabilising effect do the control systems adapted to 4MATIC conditions, such as ESP® or 4ETS, intervene to keep the CLA stable.

The 4ETS electronic traction system forms part of the ESP® electronic stability programme and brakes the driven wheels individually when they go into spin. This provides for a high level of traction on slippery surfaces, on roads which are icy on one side or in continually changing conditions. In a nutshell: while 4ETS is responsible for maintaining the highest possible traction in all conditions, ESP® serves as the higher-level control instance to ensure optimum driving stability.

Individual: driving modes to suit personal driving styles

As already mentioned, the torque distribution ratio is also dependent on the activated shift programme of the 7G-DCT dual clutch transmission. The ECO programme results in torque distribution of a conservative nature. Less torque is channelled to the rear axle, resulting in gentler handling and supporting an economical driving style at lower revs. In SPORT or MANUAL mode the activation times are shortened and more torque is distributed to the rear axle in the interests of a dynamic, sporty driving style.

On the AMG versions such as feature on the CLA 45 AMG, 4MATIC adaptation takes place in accordance with the 3-stage ESP® system, employing the user-selectable settings ESP ON, ESP SPORT Handling Mode and ESP OFF. This 3-stage stability programme is also applied to adapt the control strategies of the variable 4MATIC system. The new AMG 4MATIC applies more rear-biased torque distribution as a general principle, in order to increase lateral dynamics around the vehicle's vertical axis.

Detailed investigations in the testing phase

Alongside exact and realistic simulation using a digital prototype, extensive practical testing remains integral to the development phase of new models and drives. For the new 4MATIC, endurance testing and detailed tuning trials were carried out in all climatic zones and on all possible types of roads and surfaces. The test engineers carried out their work at test sites beyond the Arctic Circle and in desert regions, as well as trials closer to home at the Daimler test sites in Papenburg and Boxberg. Fine tuning of the control systems took place on race tracks such as the legendary Nürburgring Nordschleife and demanding alpine passes.

The test programme was backed up with extensive trials under standardised conditions on the all-wheel drive test rigs in Stuttgart-Untertürkheim. The entire powertrain with engine is set up on these large-scale test rigs and subjected to punishing treatment around the clock, following previously recorded and digitised test routes. Driving resistance is simulated here by four electric motors connected to the hubs of the respective wheels. This enables exact comparison of different design variants under standardised conditions without weather influences or changing road conditions, to reveal the best solution.

The test rig runs are also important for the purpose of tuning individual parameters. An example here is provided by the power take-off unit (PTU), which shares a common oil circuit with the main transmission in the interests of minimising component weight and maximising efficiency. As the lubricant supply process cannot be simulated exactly using a computer model, the engineers have come up with an "x-ray trick". They produce the housing in a robust, transparent material and install this "glass PTU" in the powertrain. HD cameras can then be used to provide a perfect view of the oil circuit during the subsequent runs on the test rig and optimisation measures can duly be carried out as necessary.

The above-described large-scale test rig demonstrates Daimler AG's commitment to maximum environment-friendliness and resource conservation with regard to the design and operation of test facilities. The four electric motors function as generators during braking, feeding the recuperated energy back into the power grid – at Mercedes-Benz, recuperation is not limited to the vehicles themselves.

Perfect duo: new 4MATIC and 7G-DCT dual clutch transmission

Drawing on over 50 years of experience in the development and production of automatic transmissions, Mercedes-Benz has ventured into new technical territory with the 7G-DCT dual clutch transmission: the new system is an automated three-shaft manual transmission consisting of two subtransmissions, each with its own clutch. Both actuation of the clutches and gear shifting take place fully automatically and without any interruption in tractive power. This enables a comfortable but nevertheless dynamic mode of driving. Thanks to its seven gears it offers a large gear ratio spread of up to 7.99. This means that a very short transmission ratio is available when moving off on an uphill slope with a high payload, for example, while during cruising the engine speed can be lowered considerably. The transmission's efficiency improves fuel economy by up to 9 percent in comparison to the CVT which has been employed in the A-Class to date, bringing fuel consumption down to a level below that obtained with a manual transmission.

At a length of 367 millimetres and a weight of 86 kilograms, the 7G-DCT is more compact and lighter than the transmissions in this torque class which have been available on the market to date. The clutches take the form of oil-cooled multi-disc clutches. The specially developed hydraulic fluid is actively cooled, thus ensuring correct functioning of the transmission even under extreme conditions, despite the comparatively low filling level of six litres. Excess engine heat can also be transferred to the transmission, which improves its efficiency.

For the first time on this type of unit, the transmission is supplied with oil by two oil pumps – one mechanical and one electric. The electric pump maintains the oil pressure when the engine is switched off via the start/stop function. This means that the transmission is immediately operational when the engine is restarted and the vehicle can move off again without any delay. In addition, the electric pump is able to support the mechanical pump when peak loads apply, enabling a more compact and efficient design for the mechanical pump.

Another new feature is electrical activation of the hydraulics for the parking lock, which is locked by mechanical means. This "park by wire" function enables the transmission selector lever to be positioned as desired: it is located in the form of a steering column lever on the right behind the steering wheel. In combination with the electric parking brake, additional space has thus been created in the centre console for additional stowage facilities.

Three gearshift programmes are available to the driver:

- ECONOMY: in this mode, the transmission performs gearshifts fully automatically and particularly comfortably. The gears are selected with due regard to a particularly economical style of driving at low revs

- SPORT: the transmission performs gearshifts fully automatically. The shift and response times are shorter, with gearshifts at higher engine speeds

- MANUAL: in this mode, the driver operates the transmission manually via shift paddles behind the steering wheel. The engine speeds at which the gears are shifted can therefore be freely chosen

In ECO or SPORT mode, the driver is still able to intervene manually in the gear-shifting process via the shift paddles. The transmission reverts to the selected automatic mode after the paddles have remained inactive for ten seconds, or after a longer delay when driving downhill or on winding roads.

Credits: Daimler AG

Copyright © 2012, mercedesgla. All rights reserved.

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The summit of perfection with new 4MATIC: All-wheel drive for all – tailor-made solutions

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From next year, Mercedes-Benz will be offering a new generation of the 4MATIC permanent all-wheel drive system with fully variable torque distribution. This totally new development is based on the front-wheel drive architecture with transversely mounted engines. Like the other 4MATIC versions, it boasts high tractive power reserves and outstanding agility accompanied by optimum driving safety and energy efficiency. The new 4MATIC will complement the four all-wheel drive versions which have been available to date. This will ensure 4x4 technology tailored to the respective vehicle categories – from the new compact class and the models of the C-, E-, S-, CLS- and CL-Class to the comprehensive range of SUVs and ATVs covering the GLK-, M-, GL-Class and G-Class. The new 4MATIC will also boost driving enjoyment in the two particularly dynamic Mercedes-Benz CLA and CLA 45 AMG models. Both of these models will be premiered in 2013.

The most innovative components of the new 4MATIC include the power take-off to the rear axle which is integrated in the 7G-DCT automated dual clutch transmission and the rear-axle gear unit with integrated, electrohydraulically controlled multi-disc clutch. This set-up enables fully variable distribution of the drive torque between front and rear axle. Additional benefits of this design are a lower system weight than is available from the competition and high efficiency. Similarly to the front-wheel drive versions, all 4MATIC models also boast good energy efficiency.

The 4MATIC all-wheel drive is a completely new development tailored to the requirements of the new models with front-wheel drive. The future all-wheel drive line-up from Mercedes-Benz will be heralded in the coming year by the CLA-Class and the particularly agile and powerful CLA 45 AMG. While the technical basis is identical on all versions, the AMG models feature a modified power output to the rear axle.

Integrated power take-off unit (PTU) channels power to the rear axle

The new 4MATIC is being combined with the 7G-DCT seven-speed automated dual clutch transmission which was premiered in the B-Class. The power flux to the rear powertrain is provided by a compact power take-off unit (PTU) which is fully integrated in the main transmission and is supplied with lubricant from the latter's oil circuit. This configuration gives rise to substantial weight advantages in comparison to rival systems which branch off power by means of an add-on component with its own oil circuit. Together with the friction-minimised tapered roller bearings, the PTU achieves an excellent level of efficiency.

The low system weight of the new 4MATIC is not attributable solely to the PTU. Other weight-stripping measures include a compact rear-axle gear unit, inductively hardened rear-axle side shafts in hollow design and weight-optimised propeller shafts. The system weight of the new 4MATIC is up to 25 percent lighter than the all-wheel drive versions offered by the competition.
The two-part cardan shaft is vibrationally decoupled, with an axially moving joint at the front compensating the movements of the engine-transmission unit and preventing transfer to the rear powertrain. To minimise crash-induced stress, the cardan shaft is fitted with a crash joint.

Completely new development with torque-on-demand rear axle

The electrohydraulically actuated multi-disc clutch integrated in the rear axle gear unit is responsible for fully variable torque distribution. Operating principle: when the multi-disc clutch is open, the CLA is driven almost exclusively by the front axle. When the clutch is closed, the rear axle comes into play. This means that the drive torque can be shifted in fully variable mode between front and rear axle according to the given situation (torque on demand).

The system pressure to activate the rear axle is supplied in milliseconds by the rotor-type pump which is integrated in the rear-axle gear unit. The pump is activated automatically as soon as only minimal speed differences apply between front and rear axle. Pressure control is performed by a proportioning valve under the steering of the ESP®.

Intelligent control systems for more enjoyable driving

The 4MATIC is activated according to the basic principle of "as often as necessary, as rarely as possible". This means that when the underlying conditions allow, the all-wheel drive CLA models run almost exclusively in particularly economical front-wheel drive mode. As soon as the driving situation requires, drive torque is channelled to the rear axle as appropriate. The reverse process takes place just as quickly: as soon as additional drive torque is no longer necessary at the rear axle – e.g. in case of heavy braking manoeuvres with ABS intervention – the rear powertrain is deactivated and torque is reduced to zero.

In case of understeering or oversteering under load, the drive torque is first of all distributed such as to stabilise the vehicle. Only if these measures fail to have a stabilising effect do the control systems adapted to 4MATIC conditions, such as ESP® or 4ETS, intervene to keep the CLA stable. With this strategy, the developers have managed to combine two key requirements defined in the performance specifications: optimum energy efficiency coupled with maximum driving dynamics and driving safety.

Individual: driving modes to suit personal driving styles

The torque distribution ratio is also dependent on the activated shift programme of the 7G-DCT dual clutch transmission. The ECO programme results in torque distribution of a conservative nature. Less torque is channelled to the rear axle, resulting in gentler handling and supporting an economical driving style at lower revs. In SPORT or MANUAL mode the activation times are shortened and more torque is distributed to the rear axle in the interests of a dynamic, sporty driving style. On the AMG versions, adaptation of the 4MATIC controller takes place in accordance with the 3-stage ESP®.

New 4MATIC featuring in the Mercedes-Benz CLA

The future all-wheel-drive line-up from Mercedes-Benz will be heralded in the coming year by the CLA-Class and the particularly agile and powerful CLA 45 AMG. The new Mercedes-Benz CLA adopts the avant-garde design of the Concept Style Coupé into series production almost 1:1. In keeping with its sporty positioning, the CLA is available with high-torque turbo engines rated at up to 155 kW (211 hp), sports suspension and the newly developed 4MATIC. The technical highlights include numerous driving assistance systems, such as advanced COLLISION PREVENTION ASSIST.

CLA 45 AMG: the most dynamic way to experience the new 4MATIC

As the high-powered top model of the new compact class, the CLA 45 AMG broadens the portfolio of Mercedes-Benz's high-performance brand to offer a fascinating high-performance vehicle in this class, too. The newly developed AMG 2.0-litre four-cylinder turbo petrol engine will set new standards in its engine capacity segment: with maximum torque of well over 400 Newton metres and low fuel consumption, AMG is aiming to lead the competition. In conjunction with the specially adapted 4MATIC version for this engine-power class, the CLA 45 AMG will be one of the most dynamic, powerful and efficient four-cylinder series-production compact cars.

Elegant in all weathers: the CLS Shooting Brake 4MATIC

The CLS Shooting Brake sees Mercedes-Benz making its mark once again with a creative design concept that underscores its leading role in the design field. Surprising yet unequivocally coupé, the CLS Shooting Brake's proportions create a crouched posture, as if the vehicle were poised to make a leap: long bonnet, narrow window profile with frameless side windows, roof sloping dynamically towards the rear and continuing to the tail end of the vehicle. Only at second glance does it become clear that the Shooting Brake actually has five doors and offers more in terms of functionality. In essence it represents an unprecedented version of a sports car with five seats and a large tailgate.

Like all 4MATIC models from Mercedes-Benz, the high-powered and high-torque CLS 350 CDI 4MATIC (195 kW/265 hp, 620 Nm) and CLS 500 4MATIC (300 kW/408 hp, 600 Nm) feature a permanent all-wheel drive system which guarantees optimum traction and the best possible agility and safety – particularly in wintry road conditions.

New GL- and GLK-Class all set for their first winter

The new GL-Class which is available from November 2012 is the pinnacle of perfection in the ATV and SUV world. It offers a luxurious interior with seven full-size seats and superlative ride comfort accompanied by highly dynamic performance on dry, wet or wintry roads. The premium SUV also boasts outstanding off-road capabilities, thanks to new suspension developments and innovative dynamic handling control systems which enhance both driving pleasure and safety on the road. In a nutshell, the GL-Class is a seven-seater, all-terrain S-Class.

The optional ON&OFFROAD package for the GL-Class uses six different driving modes to optimise driving dynamics and handling safety by providing the optimum drive control needed to cope with the wide spectrum of operating conditions encountered both on and off road. Drivers have the choice of an automatic mode, two specially programmed off-road modes as well as three on-road modes – "Winter", "Sport" and "Towing". The winter driving mode of the ON&OFFROAD package improves handling on glazed frost, snow and ice or when using snow chains and offers additional safety.

When the ON&OFFROAD package is combined with another optional feature, the ACTIVE CURVE SYSTEM, a specially programmed winter set-up offers dynamic driving pleasure while giving the driver excellent control over the vehicle for a high degree of handling safety. At the same time, the system is capable of giving the GL-Class greater traction, especially in wintry road conditions with low grip levels. What’s more, this set-up boasts even greater directional stability in tighter corners thanks to a special control algorithm that is programmed into the system.

April witnessed the premiere of the second new SUV to be launched in 2012: the revamped GLK-Class from Mercedes-Benz. This SUV is now able to demonstrate its outstanding capabilities in wintry conditions, too. Its claim to leadership of the compact SUV segment is underscored by trailblazing assistance systems, engines matching efficiency with agility, a new design and an extended range of equipment and appointments.

The 4MATIC on the GLK is based on the version featuring on the C-, E-, CLS- and S-Class, whereby its outstanding off-road capability sets it apart from the saloons and coupés, however. For keen off-road enthusiasts, an Offroad Engineering package is additionally available to further broaden the scope for off-road adventures. At the touch of a button a special drive programme is started which varies the shift points of the 7G-TRONIC, "softens" the accelerator characteristics and activates the ESP® off-road functions with off-road ABS and a special off-road 4ETS system. An additional switch activates Downhill Speed Regulation (DSR).

Even the best all-wheel drive is no substitute for winter tyres

Like any other all-wheel drive system, the 4MATIC versions have to abide by the laws of driving physics. The fundamental rule is that a tyre is only able to transfer a certain level of overall force to the road surface. If a particularly high degree of longitudinal force is required during acceleration or braking, for example, the available lateral force is reduced. When cornering, the reverse applies: now a large amount of lateral force is required to keep the vehicle on course, while the longitudinal force potential is restricted. The engineers' skill in designing the drive mechanism and fine-tuning the control systems lies in their ability to exploit these correlations in such a way as to ensure the best possible handling characteristics under all conditions. The frictional coefficient µ describes the physical grip between the tyres and the ground. This figure is high on a dry road (µ = 0.9) and low on a snow-covered road (µ = 0.3).

Despite all the engineers' efforts, it is ultimately the drivers themselves who determine how safe they are out on the road. They should always adapt their driving style in accordance with the prevailing wintry conditions and ensure that their vehicle is suitably equipped; winter tyres are absolutely essential here.

The full works: the 4MATIC range from Mercedes-Benz

In addition to the described models, the 4MATIC range also extends to the saloon and estate versions of the E- and C-Class, the luxurious S-Class, the CL luxury coupé, the four-door CLS Coupé and the R-Class. The M-Class and the legendary G-Class round off the range in the SUV and ATV segment. The all-wheel drive line-up from Mercedes-Benz also includes an exotic model in the guise of the SLS AMG Electric Drive. Four electric motors on this vehicle guarantee tremendous thrust, with fully variable and selective drive torque distribution to the individual wheels. In all, the 4MATIC range currently comprises 51 models. And when the compact models featuring the new 4MATIC generation round off the range next year, it will really be a case of all-wheel drive all-round! The 4x4 family from Mercedes-Benz will then cover almost 60 models.

Credits: Daimler AG

Copyright © 2012, mercedesgla. All rights reserved.

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Newly developed 4MATIC all-wheel drive for the new CLA: All-wheel drive for all

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From next year, Mercedes-Benz will be offering a new variant of the 4MATIC permanent all-wheel-drive system with fully variable torque distribution. This new development is based on the front-wheel-drive architecture with transversely mounted engines. Like the other 4MATIC versions, it boasts high tractive power reserves and outstanding agility accompanied by optimum driving safety and energy efficiency. The new 4MATIC will complement the four all-wheel-drive versions which have been available to date. This will ensure 4x4 technology tailored to the respective vehicle categories – from the CLA and the models of the C-, E-, S-, CLS- and CL-Class to the comprehensive range of SUVs and ATVs covering the GLK-, M-, GL-Class and G-Class. The new 4MATIC will also boost driving enjoyment in the particularly dynamic CLA 45 AMG which, like the series production model, is to be premiered in 2013.

The most innovative components of the new 4MATIC include the power take-off to the rear axle which is integrated in the 7G-DCT automated dual clutch transmission and the rear-axle gear with integrated, electrohydraulically controlled multi-disk clutch. This set-up enables fully variable distribution of the drive torque between front and rear axle. Additional benefits of this design are a lower system weight than is available from the competition and high efficiency. Similarly to the front-wheel-drive versions, all 4MATIC models also boast good energy efficiency.

The 4MATIC all-wheel drive is a completely new development tailored to the requirements of the new models with front-wheel drive.

Integrated power take-off unit (PTU) channels power to the rear axle

The new 4MATIC comes together with the 7G-DCT seven-speed automated dual clutch transmission. The power flux to the rear powertrain is provided by a compact power take-off unit (PTU) which is fully integrated in the main transmission and is supplied with lubricant from the latter's oil circuit. This configuration gives rise to substantial weight advantages of up to 25 percent in comparison to rival systems which branch off power by means of an add-on component with its own oil circuit. Together with the friction-minimised tapered roller bearings, the PTU achieves an excellent level of efficiency.

Completely new development with torque-on-demand rear axle

The electrohydraulically actuated multi-disk clutch integrated in the rear-axle gear unit provides for fully variable torque distribution. Basic principle: when the multi-disk clutch is open, the vehicle is driven almost exclusively by the front axle. When the clutch is closed, the rear axle comes into play. The drive torque can be shifted in fully variable mode between front and rear axle according to the given situation (torque on demand).

The system pressure to activate the rear axle is supplied in milliseconds by the rotor pump which is integrated in the rear-axle gear unit. The pump is activated automatically as soon as only minimal speed differences apply between front and rear axle. Pressure control is performed by an ESP®-controlled proportioning valve.

Intelligent control systems for enjoyable driving

The 4MATIC is activated according to the basic principle of "as often as necessary, as rarely as possible". This means that when the underlying conditions allow, the all-wheel-drive models run almost exclusively in particularly economical front-wheel-drive mode. As soon as the driving situation requires, drive torque is channelled to the rear axle as appropriate. The reverse process takes place just as quickly: as soon as additional drive torque is no longer necessary at the rear axle – e.g. in case of heavy braking manoeuvres with ABS intervention – the rear powertrain is deactivated and torque is reduced to zero.

In case of impending understeering or oversteering under load, the drive torque is first of all distributed such as to stabilise the vehicle. Only if these measures fail to have a stabilising effect do the control systems adapted to 4MATIC conditions, such as ESP® or 4ETS, intervene to keep the vehicle stable.

With this strategy, the developers have managed to combine two key requirements defined in the performance specifications: optimum energy efficiency coupled with maximum driving dynamics and driving safety.

Individual: driving modes to suit personal driving styles

The torque distribution ratio is also dependent on the activated shift programme of the 7G-DCT dual clutch transmission. In ECO mode less torque is channelled to the rear axle, resulting in gentler handling and supporting an economical driving style at lower revs. In SPORT or MANUAL mode the activation times are shortened and more torque is distributed to the rear axle in the interests of a dynamic, sporty driving style. On the AMG versions, adaptation of the 4MATIC controller takes place in accordance with the 3-stage ESP®.

New 4MATIC featuring in the Mercedes-Benz CLA

The CLA-Class models which are set to appear next year and the particularly agile and powerful CLA 45 AMG will also benefit from the further advances in all-wheel-drive technology from Mercedes-Benz. The new Mercedes-Benz CLA adopts the avant-garde design of the Concept Style Coupé into series production almost 1:1. In keeping with its sporty positioning, the CLA is available with high-torque turbo engines rated at up to 155 kW (211 hp), sports suspension and the newly developed 4MATIC. The technical highlights include numerous driving assistance systems, such as advanced COLLISION PREVENTION ASSIST.

CLA 45 AMG: the most dynamic way to experience the new 4MATIC

As the high-powered top model of the new compact class, the CLA 45 AMG broadens the portfolio of Mercedes-Benz's high-performance brand to offer a fascinating high-performance vehicle in this class, too. The newly developed AMG 2.0-litre four-cylinder turbo petrol engine will set new standards in its engine capacity segment: with maximum torque of well over 400 Newton metres and low fuel consumption, AMG is aiming to lead the competition. In conjunction with the specially adapted 4MATIC version for this engine-power class, the CLA 45 AMG will be one of the most dynamic, powerful and efficient four-cylinder coupés around.

Impressive variety

In addition to the E-Class and the C-Class, both of which are available as Saloon and Estate variants, the 4MATIC model range also extends to the CL luxury coupé, the four-door CLS Coupé and the CLS Shooting Brake. The recently thoroughly overhauled SUVs and ATVs are also included in the range – the M‑Class, the compact GLK, the GL luxury SUV and the legendary G-Class, which still retains its special off-road strengths after 33 years in production. The all-wheel-drive line-up from Mercedes-Benz further includes an exotic model in the guise of the SLS AMG Electric Drive. Four electric motors on this vehicle guarantee tremendous thrust, with fully variable and selective drive torque distribution to the individual wheels. And when the compact models featuring the new 4MATIC generation round off the range next year, it will really be a case of all-wheel drive all-round!Newly developed 4MATIC all-wheel drive for the CLA: All-wheel drive for all

Credits: Daimler AG

Copyright © 2012, mercedesgla. All rights reserved.

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Mercedes-Benz Frontbass and Signature Sound: The new benchmark for car audio systems

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The bass sounds come from the foot space at the front, high and mid-range tones are virtually at the same level as the occupants’ ears, and the music sounds as it would live on the surround sound stage: with the Frontbass sound system, which is unique in the world, and the first music DVD specially produced for the acoustic space of a car and directly mixed in 5.1 Surround Sound, an entirely new listening experience awaits Mercedes-Benz music connoisseurs. This year, both innovations celebrated their premiere in the new Mercedes-Benz SL. The Frontbass sound system, in particular, will be installed in other Mercedes models in future.

With the “Mercedes-Benz Signature Sound”, the internationally renowned and two-times Grammy award-winning music expert, Herbert Waltl, Senior Producer and CEO of mediaHYPERIUM, has produced a music DVD that has been mixed and mastered precisely to the Frontbass sound system, the specific acoustic surroundings, and the position of the driver and front seat passenger in the new Mercedes-Benz SL. In doing so, he has developed a unique production concept in the surround sound process for the ultimate musical experience in a car. “Conventional audio systems for cars create the surround sound with computer-generated processes. The somewhat more hands-on approach of my Signature Sound production concept brings back the artistic element and the original emotional element of the musical interpretation. This improves the audio quality and enhances the musical authenticity,” explains Waltl, who is considered the international guru of surround sound audio production, and who was the first DVD video producer in music history.

Reproduction of the artists’ intended original sound

In collaboration with the sound experts from Mercedes-Benz, Waltl selected 15 well-known rock and pop songs, along with ten masterpieces from the world of classical music. The tracks include “Cold As Ice” by Foreigner, “Poker Face” by Lady Gaga, “Everyday Is A Winding Road” by Sheryl Crow, the “Violin Concerto K 218” by Wolfgang Amadeus Mozart and “Symphony No. 5” by Ludwig van Beethoven. In order to adhere as closely as possible to the artists’ intended original sound, he procured the rights to the pieces of music, and also the soundtracks for the original studio recordings (which for some of the pieces consist of up to 200 individual tracks), as well as the original stereo CD for comparison purposes.

For the remixing, he secured the services of the internationally recognised sound engineer, Leslie Ann Jones, Director Music Recording and Scoring at Skywalker Sound, the legendary sound studio of director George Lucas in California. Mercedes-Benz provided an SL model, which was placed in the recording studio. “For the first time, this allowed us to mix the music exactly for the space in which it would later be heard. This is unique in the history of music production,” says Leslie Ann Jones, three-times Grammy award-winning sound engineer. Jones first reconstituted the original mix for each piece to ensure the greatest possible authenticity in terms of artistic intent. She then placed the difference sound elements on the surround sound stage, and, with meticulous attention to detail, balanced the mix to the acoustic space of the SL and the Frontbass sound system. It was a very elaborate process, involving mixing in the control room, listening in the car, fine adjustments in the control room and so on.

The perfect surround sound for the ultimate musical experience in a car

With the “Signature Sound” music DVD and the Frontbass sound system in the new SL, Mercedes-Benz has combined the very best in music production with the very best in car audio technology, creating the new benchmark for car audio systems. In the following interview, Ralf Lamberti, Director Advance Development Telematics at Mercedes-Benz, Herbert Waltl and Leslie Ann Jones explain the advantages of both innovations.

Mr Lamberti, how did Mercedes-Benz come up with the idea of installing the woofers in the foot space?
Ralf Lamberti: We have been working on this idea since 2005 in our efforts to improve further the sound quality in the vehicle. The standard location for the woofers in the doors produces disruptive acoustic vibrations. And with roadsters and convertibles, there is the added problem that sounds are literally blown away by the airstream when the roof is down. All that remains is a muffled sound layer. We wanted to change that situation. However, with traditional vehicle shell structures, it has not been possible to move the woofers into the foot space – there was simply not enough installation or resonating space. We have now created this space in the new SL. The two longitudinal front members in the aluminium frame structure were designed in such a way that the loudspeakers could fit directly into two openings in the firewall on either side of the foot space. Cavities in the longitudinal members behind the loudspeakers act as resonating chambers. And the foot space in front of the speakers forms a funnel that bundles the sound.

And what is the result?
Ralf Lamberti: Clear, crisp and distortion-free bass sounds over the entire frequency range. Thanks to the installation position low down in the foot space, the dominant sound remains in the vehicle, even when the roof is down. Another benefit is that the relocation of the woofers opens up additional free space. We were able to find ideal positions for the mid-range and tweeters in the doors, the dashboard and in the vehicle rear close to the beltline, and thus almost level with the SL occupants’ ears. This gives a precise, brilliant sound, just like in a concert hall. The result is an exact stage reproduction with precise instrument positioning and equally precise spatial graduation. To make this unique surround sound experience even more intensive, we produced the “Signature Sound” DVD in collaboration with Herbert Waltl. So we are combining the very best in car audio technology with the very best in music production.

Mr Waltl, you are considered the guru of surround sound audio production. What prompted you to develop a special surround sound concept especially for a car?
Herbert Waltl: A car is actually a perfect place to enjoy surround sound. But the majority of playback devices in cars use only the stereo mixes for the sound reproduction, whereas surround sound is created by the audio system itself in a computer-controlled process. This artificial re-mixing is necessary because the acoustics and the positioning of the loudspeakers in a car are totally different from what you would have in any other space. But the automated mixing process generally doesn’t produce the listening experience that the artists intended to create when they recorded the music in the studio, and much of the artistic intent is lost. This gave me the idea of developing a special surround sound production concept for a car, where the focus would be on the “artistic” side of the music. In Mercedes-Benz and Leslie Ann Jones, who is one of the top sound engineers in the world, I found the perfect partners for these very specific music mixes.

Ms Jones, what are the special features of the “Signature Sound” mixing?
Leslie Ann Jones: The pieces of music were mixed directly in the 5.1 surround sound process and tweaked precisely for the space in which they will ultimately be heard – the Mercedes-Benz SL. The car was right there in the studio. We were able to mix precisely the representation of the instruments and the singing, and the spatial graduation of each piece of music for the acoustic environment of the roadster, the positioning of the individual loudspeakers, and thus also for the seat position of the driver and front seat passenger.

We worked with the soundtracks from the original recordings, and we stuck closely to the original sound ideas of the artists. The result is the ultimate listening experience that is just like on a surround stage – more authentic and in better audio quality that you will find on any standard CD or DVD.

What part did the Frontbass technology play?
Herbert Waltl: It is a significant advantage, of course, to produce music for a good playback system with a superb bass sound – and the Frontbass system is exceptional. It delivers a crystal-clear, transparent bass reproduction, allowing the sound engineer to work on very specific details during mixing and mastering. The Frontbass system and the “Signature Sound” concept are a perfect combination for achieving a really intensive and artistic music experience in the car. It’s a feast for the ears, where you feel as if you are at a live concert on the best seats in the middle of the audience.

Will Frontbass and “Signature Sound” also be introduced into other Mercedes model series?
Ralf Lamberti: We are currently working on progressively introducing the Frontbass system into other vehicle models. In principle, the “Signature Sound” concept can also be transferred to other high-end car sound systems. We’re considering placing the concept on a broader footing – even without using Frontbass technology. However, the rule is the better the audio technology used to play music produced with the “Signature Sound” concept, the better the listening experience – and the Frontbass technology is the best we have just at the moment.

Credits: Daimler AG

Copyright © 2012, mercedesgla. All rights reserved.

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The all new Mercedes-Benz CLS Shooting Brake: The drive system - Powerful and efficient

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Common hallmarks of all five of the engines deployed in the Mercedes-Benz CLS Shooting Brake are superlative efficiency and the ultimate in driving enjoyment. The two diesel drives and three petrol engines also all feature a 7-speed automatic transmission and the ECO start/stop function. Two models with all-wheel drive are additionally available: CLS 350 CDI 4MATIC BlueEFFICIENCY and CLS 500 4MATIC BlueEFFICIENCY. Absolute peak performance is embodied by the CLS 63 AMG Shooting Brake.

The entry-level model is the CLS 250 CDI BlueEFFICIENCY with a power output of 150 kW (204 hp). Fuel consumption in combined mode is outstanding for this power category, at 5.3 litres of diesel per 100 kilometres, corresponding to CO2 emissions of 130 grams per kilometre. On the next level come the two six-cylinder engines: the CLS 350 CDI BlueEFFICIENCY rated at 195 kW (265 hp) and the CLS 350 BlueEFFICIENCY with a power output of 225 kW (306 hp). The V8 biturbo engine of the CLS 500 BlueEFFICIENCY generates an output of 300 kW (408 hp). The top model is the CLS 63 AMG, delivering up to 410 kW (557 hp).

An all-rounder: the four-cylinder diesel engine of the CLS 250 CDI

From the S-Class through the M-Class to the C-Class, the top version of the four-cylinder direct-injection engine measures up on all fronts while setting efficiency benchmarks in the luxury segment. In the second generation of the four-door Coupé it is being offered in this segment for the first time, as the CLS 250 CDI BlueEFFICIENCY. With an output of 150 kW (204 hp), a top speed of 235 km/h and a full 500 Nm of torque, it offers unbridled driving enjoyment while surprising the driver at the filling station with fuel consumption on a par with that of a compact car: on average, the CLS Shooting Brake gets by on 5.3 litres per 100 km, corresponding to CO2 emissions of 139 g/km.

The ultimate diesel: the V6 engine of the CLS 350 CDI

195 kW(265 hp) and 620 Newton metres of torque: The large diesel engine in the CLS 350 CDI BlueEFFICIENCY is a highly refined power house. Its performance figures are suitably impressive: the Shooting Brake accelerates to 100 km/h from a standing start in 6.6 seconds, and the top speed is 250 km/h. Ample tractive power and sporty performance are accompanied by exemplary fuel efficiency: in combined mode, the V6 runs on 6.0 litres per 100 km, while CO2 emissions stand at 159 g/km.

The Mercedes engineers carried out a thorough overhaul of the engine for the launch of the CLS Coupé. It now has improved engine management in the form of new-generation control units and new software, new sensors and actuators, and more efficient aftertreatment in the maintenance-free diesel particulate filter system with reduced back-pressure. In addition to more effective cooling of recirculated exhaust gas using a variable bypass valve, the in-engine measures include a reduction of the compression ratio from 17.7:1 to 15.5:1, an optimised VNT turbocharger with low-friction shaft bearings for greater agility and high output, new injection nozzles and revised ducting in the intake tract. A whole package of measures has resulted in substantial fuel savings: apart from the ECO start/stop function, these also include generally lower in-engine friction (through precision honing of the cylinder walls, amongst other measures), more efficient thermal management, an improved compound oil pump and modified cylinder head cooling.

The V6 diesel engine is also deployed in the CLS 350 CDI BlueEFFICIENCY 4MATIC.

Petrol engine with BlueDIRECT: the most efficient form of direct injection

The second generation of direct petrol injection made its debut in the CLS 350 CGI introduced in 2006. The six cylinder unit was the world's first petrol engine with piezo-electric direct injection and spray-guided combustion, and as such achieved a fuel saving of around ten percent compared with its predecessor with port injection.

The current CLS features third-generation direct petrol injection. The innovation which goes by the name of BlueDIRECT has established the V-engines from Mercedes-Benz as worldwide benchmarks, both by virtue of their elegantly powerful thrust and in terms of fuel consumption. Key data for the CLS 350 BlueEFFICIENCY: 225 kW (306 hp), 370 Nm, 7.3 litres of fuel per 100 km, 169 g CO2 per km. The CLS 350 BlueEFFICIENCY accelerates from zero to 100 km/h in 6.7 seconds and attains a top speed of 250 km/h.

Direct petrol injection with spray-guided combustion, which Mercedes-Benz was the first car manufacturer to introduce in series production, disposes of a system pressure of up to 200 bar as the third-generation BlueDIRECT injection system, with variable optimisation of the pressure level according to the engine's characteristic map. Piezo-electric injectors allow up to five injections per power stroke for the best possible mixture formation, while multi-spark ignition helps to ensure reliable combustion of the mixture. Key features of the V6 petrol engine with BlueDIRECT technology in the CLS 350 BlueEFFICIENCY are:

- 60° cylinder angle, no balancer shaft

- Extended lean-burn operation, lean-burn system with load monitoring from pressure information, new combustion system operating modes

- Multi-spark ignition

- Resonance intake manifold

- Latest generation of piezo injectors

- Enhanced cooling circuit control and optimisation

- Enhanced oil circuit control and optimisation

- Increased output and torque

V8 biturbo: the ultimate in refined sportiness

While V6 is a naturally aspirated engine, the technically closely related V8 engine in the CLS 500 BlueEFFICIENCY features biturbo-charging. The V8 also disposes of direct injection, but it has been designed for countries in which sulphur-free fuel is not available and is thus operated in homogeneous mode throughout the entire performance map. With a cubic capacity of 4633 cc, the eight-cylinder engine delivers 300 kW (408 hp) of power and maximum torque of 600 Nm. This enables the CLS Shooting Brake to accelerate from 0 to 100 km/h in 5.3 seconds while maintaining exemplary fuel efficiency for its power category at 9.2 l/100 km, corresponding to CO2 emissions of (214 g/km). The V8 biturbo is also available as a CLS 500 BlueEFFICIENCY 4MATIC variant.

CLS 63 AMG: delivering up to 410 kW (557 hp)

The AMG 5.5-litre V8 biturbo engine impresses with a combination of direct petrol injection with spray-guided combustion, piezo injectors, biturbocharging, air/water intercooling, generator management and ECO start/stop function.

The eight-cylinder engine is the embodiment of pure dynamism and high efficiency: offering power output and torque levels of 386 kW (525 hp) and 700 Nm respectively, the effortless superiority of the CLS 63 AMG Shooting Brake can be enjoyed by the driver over every single kilometre. In conjunction with the "Edition 1", these figures are pushed to 410 kW (557 hp) and 800 Newton metres. Both variants offer driving performance of the highest calibre: accelerating from zero to 100 km/h takes 4.4 and 4.3 seconds respectively, and the top speed is 250 km/h (electronically limited).

Overview of the engine programme for the CLS Shooting Brake (figures for 4MATIC versions in round brackets, for CLS 63 AMG "Edition 1" in square brackets):

7G-TRONIC PLUS automatic transmission also available with the four-cylinder diesel engine

All CLS models apart from the CLS 63 AMG come with the 7G-TRONIC PLUS automatic transmission as standard. The current generation of the torque converter provides an improved dynamic response, better durability and reduced noise and vibration levels thanks to a new hydraulic circuit, as well as enhanced dampers and torque converter housing. The extreme wheel-slip reduction of the torque converter housing, combined with larger mechanical damper de-coupling, helps to reduce consumption significantly. In addition, the gearshift program in ECO mode has been changed in favour of lower engine rpm at cruising speeds.

AMG SPEEDSHIFT MCT 7-speed sports transmission – individual and flexible

The CLS 63 AMG Shooting Brake is fitted with the AMG SPEEDSHIFT MCT 7-speed sports transmission. Equipped with four individual transmission modes as well as automatic double declutching and RACE START functions, its power delivery is characterised by responsiveness and maximum variability. In "Controlled Efficiency" (C) mode, the ECO start/stop function is always enabled and switches the eight-cylinder engine off when the vehicle is at a standstill. In "S" (Sport), "S+" (Sport plus) and "M" (Manual) transmission modes, the engine and transmission are significantly more responsive: short, precisely defined interruptions of ignition and injection result in faster gear changes under full load.

4MATIC all-wheel drive: superior traction, whatever the conditions

The all-wheel drive is designed as a permanently operative drive mechanism. This offers crucial advantages over other systems, which activate all-wheel mode only after detecting a lack of traction. In contrast, the 4MATIC transfers drive torque via the wheels to the road without any interruption. In addition, the Shooting Brake offers quiet running and vibrational comfort in line with the high standards expected of vehicles from Mercedes-Benz.

When pulling away in slippery conditions, the 4MATIC models are designed

to develop maximum traction. To this end, certain road conditions are automatically detected and the interventions of the 4ETS electronic traction control system adjusted so as to achieve the greatest possible acceleration while minimising wheel slip, ensuring optimum directional stability in the process. This strategy also allows the vehicle to pull away under the most adverse conditions, such as when one side of the vehicle is on an icy slope (µ-split) or both wheels on either the front or rear axle have limited grip (µ-jump).

On twisting roads covered with snow and ice, driving stability is primarily controlled by the ASR acceleration skid control system's regulation of engine torque. The ASR control thresholds are adjusted according to the driving situation based on the vehicle's longitudinal and lateral dynamic readings as continuously measured by the ESP® sensor system. If vehicle stability is to be maintained, the longitudinal force when cornering must be controlled by means of engine torque regulation in such a way that there are sufficient reserves of lateral force at all times. In order to comply with this physical correlation, when cornering on road surfaces with a low friction coefficient the control thresholds for engine torque regulation at the wheels on the outside of the bend are reduced considerably so that the tyres can develop sufficient lateral force.

As with the system’s set-up on a dry or wet road, handling stability and subsequently active safety are paramount at all times when wintry conditions prevail too in the CLS models with 4MATIC. The mechanical principle of the 4MATIC system, featuring a 45:55 torque split between the front and rear axles and a multi-disc limited-slip centre differential with a basic locking torque of 50 Newton metres, offers all the right ingredients for this.

This basic design enables high levels of traction, as the dynamic shift in axle load toward the rear axle that occurs during acceleration is harnessed to deliver more drive torque to the rear wheels. However, the multi-disc differential lock is also able to shift the drive torque between the front and rear axles, varying the split between 30:70 and 70:30 as the road conditions dictate. Consequently, intervention by the ESP®, 4ETS or ASR electronic control systems can be delayed for as long as possible and the bulk of the drive torque converted into tractive power, even on slippery roads. All control system interventions go virtually unnoticed, yet drivers still know straight away if they are driving near the limit, as a yellow warning symbol will flash in the instrument cluster. This serves as a clear prompt to adapt the driving style to the road conditions.

Credits: Daimler AG

Copyright © 2012, mercedesgla. All rights reserved.

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The new Mercedes-Benz SL 63 AMG: Chassis and braking system - Driving dynamics at the highest level

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High-performance drive and power transmission systems call for high-tech suspension and braking systems. In this area too the SL 63 AMG is able to fulfil all of the expectations which are made of it. The characteristic qualities already valued by customers in the preceding model – dynamic handling and high levels of agility, combined with the comfort on long journeys typical of Mercedes – have been optimised and refined even further by Mercedes-AMG in the new edition of the high-performance Roadster.

As with the body, the experts from Affalterbach also turned to aluminium for the AMG sports suspension too. The steering knuckles and spring links on the 4-link front axles are therefore also made of aluminium, as are virtually all of the suspension parts on the multi-link independent rear suspension. The integral support frame for the front-axle halves, steering gear and engine is also produced in aluminium. The result: the weight savings achieved compared with regular components made of steel help to reduce the unsprung masses, which in turn results in measurable and noticeable benefits in terms of the response of the spring and damper elements as well as the agility. Another significant highlight is that the SL 63 AMG has more negative camber on both axles as well as fully revised elastokinematics for a more direct driving sensation and higher lateral acceleration. Also contributing to this same effect is the track width, which is significantly wider than that of the preceding model (front axle is 52 mm wider, rear axle 50 mm wider).

Active Body Control optimised for even greater performance

Driving dynamics also feature as part of AMG's new design. The sports suspension based on Active Body Control (ABC) has come under the spotlight. During the development and testing phase, active suspension control was specially optimised in terms of cornering performance. Basically the ABC suspension all but entirely eliminates the body movements that occur when moving off, cornering on uneven road surfaces and braking. Bends are negotiated with far less roll; the body roll caused by fast evasive manoeuvring is effectively suppressed. The control elements of this system are the damper struts, in which a hydraulic servo cylinder is arranged in series with the steel spring. By retracting and extending, this cylinder actively adjusts the length of the spring and therefore the spring force of the damper strut. As a result, conventional torsion-bar stabilisers can be dispensed with on the front and rear axles.

High-performance control electronics in permanent dialogue with the engine and transmission control unit ensure that the forces of the four damper struts are adapted practically instantly. A new feature is the visual ABC display in the COMAND system menu: driver and front passenger can monitor the individual actions of the active suspension control on each of the wheels in real time.

Briefly pressing the suspension button designated with a shock absorber symbol in the AMG DRIVE UNIT changes the characteristics of the AMG sports suspension: the roll angle through fast corners is reduced further, the shock absorbers and springs also respond firmer to promote agility. In Sport mode, ABC automatically lowers the body continuously by up to 8 millimetres at speeds of between 65 and 100 km/h. In Comfort mode, lowering takes place between 140 and 170 km/h. The positive effects include reduced wind resistance and a lowering of the vehicle's centre of gravity. If more ground clearance is needed when driving on poor road surfaces or over ramps, the level of the vehicle can be raised by a maximum of 55 millimetres at speeds up to 30 km/h. 

Active Body Control also available as performance suspension

As an option, the AMG performance suspension is also available for the SL 63 AMG from the AMG Performance Studio. Damper characteristics can be made stiffer by up to 30 percent in both modes. This provides for even less body movement and is recommended when striving for high-speed laps on a closed-off racing circuit, for example.

Another notable feature of Active Body Control is the variable roll moment distribution between the front and rear axles, which the system carries out automatically according to the driving situation and speed. The computer uses various acceleration sensors to obtain information on the current driving situation and compares this data with those from the pressure sensors in the spring struts and the level sensors on the control arms. The system then computes the control signals that the servo-hydraulic valves at the front and rear axle transform into precisely metered flows of oil. In addition, the SL 63 AMG is fitted with hydraulic all-round self-levelling which helps to ensure a constant vehicle level irrespective of the load being carried.

AMG speed-sensitive sports steering with variable power assistance

One new development is the electromechanical AMG speed-sensitive sports steering: with its constant and direct ratio of 14:1, it enables a sporty response from the central position and supports the vehicle's largely linear understeer/ oversteer characteristics. The result is light-footed, agile cornering behaviour and clear feedback at critical limits.

And that is not all: for the first time, the top-of-the-range AMG model features power assistance which adapts according to the suspension mode. In "Comfort" mode, the AMG speed-sensitive sports steering responds comfortably, with a higher degree of steering assistance. In "Sport" mode on the other hand, the driver feels less steering assistance – which translates into an improved sense of road feel. This benefits both response and steering precision, particularly at high speeds and when adopting a sporty driving style.

New steering helps to save fuel

In addition to more precise steering and a more comfortable feel at the wheel, the new electric power steering offers a range of additional advantages. It makes an important contribution to efficiency, since the steering assist function only requires power when the driver actually steers. Compared with the previous model with regular hydraulic power steering, this enables savings of up to 0.3 litre/7 g CO2 per 100 km (NEDC combined) to be achieved.

Power assistance is also available when the engine is stationary, for example – whereby an algorithm ensures that the combustion engine is not prompted to start up in ECO start/stop mode when the driver is merely moving the steering wheel while the vehicle is at a standstill. The new steering system has also enabled implementation of the "Active Park Assist" automatic parking function and relieves the strain on the driver on road surfaces which slope away towards the kerb.

In the new steering system the steering gear and the supporting servo-motor form a single compact unit and are mounted on the integral support frame made of aluminium and positioned in front of the wheel's centre line. The high-performance control unit processes a variety of parameters captured by the ESP® control unit – including vehicle speed, steering angle, steering angle speed, lateral acceleration and also understeer/oversteer characteristics – and in a split second calculates the forces which the driver needs to input into the steering in different driving situations – from parking to high-speed motorway driving. Active damping enhances the feeling of safety when driving straight ahead at high speed.

3-stage ESP® system with "SPORT Handling" mode

As previously, the SL 63 AMG offers 3-stage ESP® as standard: the Electronic Stability Program supports three individual control strategies at the push of a button. The ESP® button in the AMG DRIVE UNIT allows the driver to choose between "ESP ON", "SPORT Handling" mode, and "ESP OFF" – with the currently active mode shown in the display of the AMG instrument cluster. In "ESP ON", the onset of handling instability leads to braking intervention at one or more of the wheels, accompanied by a reduction in engine torque.

Briefly pressing the ESP® button activates "SPORT Handling" mode. In this mode the braking intervention to counter oversteer or understeer, as well as the accompanying reduction in engine torque, allows a higher dynamic threshold and, for instance, corresponding drift angles – the driver benefits from significantly enhanced driving enjoyment. As soon as the driver operates the brake pedal, all of the normal ESP® functions are restored. Prolonged pressing of the ESP® button activates "ESP OFF". With this, the engine torque is no longer reduced to control the driving dynamics – and driving enjoyment is therefore increased even further. "ESP OFF" should only be used by experienced drivers on dedicated racetracks. In this mode too, all of the functions of ESP® are made available by operating the brake pedal.

The system's traction logic is active in all three ESP® modes. If one of the drive wheels starts to spin, specific brake pressure is applied to virtually create the effect of a mechanical differential lock. This means that the engine power is transferred to the road even more effectively. Traction can be improved further with the AMG rear axle locking differential available as an option from the AMG Performance Studio.

Newly developed AMG high-performance composite braking system

Along with the steering, the braking system is also a new development. The AMG high-performance composite braking system is characterised by high deceleration performance, a precise actuation point and excellent fade-resistance. Ventilated and perforated brake discs are fitted to both the front and rear axles. Because of the special stresses they face, the front discs feature composite technology that has been tried and tested in motor racing to help offset the temperature peaks more effectively. The front discs, measuring 390 x 36 mm, are decelerated using 6-piston aluminium fixed callipers, while the rear, measuring 360 x 26mm, use single-piston aluminium floating callipers. Grey-painted brake callipers with white AMG lettering are part of the standard equipment.

AMG ceramic composite high-performance brakes are available as an option and are recognisable thanks to the "AMG Carbon Ceramic" logo on the brake callipers. Thanks to the special materials and production technology used to manufacture the discs from carbon-fibre-reinforced ceramic in a vacuum at 1700 degrees Celsius, the ceramic discs are much harder. This not only increases the service life many times over compared with a grey cast iron disc, but also their resistance to extreme loads and heat. The result is extremely short stopping distances, an exact pressure point and much higher fade resistance even under extreme operating conditions. The larger ceramic discs – front: 402 x 39 millimetres; rear: 360 x 32 millimetres – feature a composite design all round and are connected with a floating radial mount to an aluminium bowl.

Compared with the conventional composite brake discs, the ceramic brake discs are around 40 percent lighter. The further reduction in unsprung masses not only boosts driving dynamics and agility but also improves steering response as well as ride comfort and contact characteristics. Six-piston fixed callipers are fitted on the front axle, and single-piston callipers are used on the rear.

Braking system data for the Mercedes-Benz SL 63 AMG at a glance:

Numerous functions of the high-performance braking system with ADAPTIVE BRAKE help to enhance comfort and safety. Take the practical HOLD function: if the SL 63 AMG has come to a stop, the driver simply needs to press the brake pedal a little bit firmer. The vehicle is now held by the brake – even if the driver takes their foot off the brake pedal. This prevents the vehicle from unintentionally rolling forward in stop-and-go traffic or inadvertently rolling back on an uphill slope. The HOLD function is automatically disengaged once the vehicle is driven forward. Another useful feature comes in the shape of the Hill-Start Assist. If the sensor technology detects that the driver wants to move off on an incline, the brake pressure is automatically maintained constant for a short period. This means the SL will not roll back and the driver has sufficient time to switch from the brake to the accelerator pedal without having to use the parking brake.

If the driver suddenly switches from the accelerator to the brake pedal prior to emergency braking, the braking system increases the pressure in the brake lines and applies the pads to the brake discs, so that they can grip instantly with full force when the brake pedal is pressed. The system supports the standard-fit Brake Assist by means of this 'priming'. Further standard features include the brake-drying function, which uses brief braking impulses to ensure the film of water on the brake discs is removed in the wet, thus considerably improving the responsiveness of the brakes.

Three light-alloy wheel variants to choose from

Three different AMG light-alloy wheels are available for the SL 63 AMG. As standard the Roadster comes with titanium grey-painted 5-twin spoke AMG light-alloy wheels with a high-sheen finish. The front axle is fitted with 255/35 R 19 tyres on 9.0 x 19 rims, while the rear has 285/30 R 19 tyres on 10 x 19 rims.

The weight-optimised AMG forged wheels from the AMG Performance Studio help to reduce the unsprung masses. Two different versions are available as an optional extra: multi-spoke AMG forged wheels in the format 9.0 x 19 (front) and 10 x 20 (rear) with 255/35 R 19 tyres on the front and 285/30 R 20 tyres on the rear – painted either in titanium grey and polished or painted in matt black with a high-sheen rim flange.

* Official photos and details courtesy of Mercedes-AMG GmbH *

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